1. Field of the Invention
The present invention relates to agricultural harvesters, and more specifically to apparatus for removably attaching a header to such harvesters.
2. Description of the Related Art
In the quest for ever increasing operational efficiency, agricultural harvesters incorporate easily removable headers to provide flexibility in the type of crop to be harvested. Along with the flexibility of changing out the header it has been a goal make the installation and removal as quick as possible but at the same time ensuring that the header, once in place, is safely secured against inadvertent disconnection.
Existing header assemblies are usually supported by a pair of lower lift arms pivotally secured to the main body of the agricultural harvester and a third arm between and above the lower lift arm. All three arms are pivotable through appropriate actuators to change the level of the header relative to the ground (and its attitude) to facilitate harvesting of varied crops. The connection between the lift arm and the header is accomplished by upwardly facing U-shaped recesses on the ends of the lift arm which mate with corresponding mounting pins on the header. In order for the mounting pins, and thus the header, to be safely secured to the agricultural harvester, a locking bar mounted on the lift arms is slidable between an unlocked position permitting installation and removal of the mounting pins and a locked position where the pins are captured in the U-shaped recesses. Because the parts are designed to lift substantial loads, the locking bar is actuated by a lever arm on the lift arm to accomplish this function. The lever arm then must be locked in its locked position so as to prevent inadvertent movement of the bar from its locked position. In the past, the locking function has been accomplished by a locking or lynch pin dropped by gravity through corresponding holes on the lever arm and the lift arm to hold it in place.
When harvesting certain crops such as canola, switch grass and miscanthus, the header does not ride close to the ground but is suspended anywhere from 2 to 18 inches off the ground. Selecting this height for the header leaves behind very tall and rigid stubble which can interfere with the pin holding the lever arm in its locked position. In fact, the pressure can be great enough to push the pin out of place. One solution to this is securing the lever in its locked position by a bolt which detracts from flexibility and speed of changing out the header.
Accordingly, what is needed in the art is a locking mechanism for a header attachment assembly that is resistant to post harvesting field conditions.